In general, a CMOS image sensor includes a photodiode region for converting a light signal to an electrical signal, and a transistor region for processing the converted electrical signal.
Typically, the photodiode and the transistor are arranged horizontally on a substrate. This arrangement may be referred to as a horizontal type CMOS image sensor.
That is, in a horizontal type CMOS image sensor according to the related art, a photodiode and a transistor are formed adjacent to each other for each unit pixel on a substrate. Therefore, an additional region in the pixel area of each unit pixel is required for the photodiode. This decreases a fill factor region and can limit the possibility of resolution.
Also, according to the related art, the image quality of the image sensor may become deteriorated due to a crosstalk between pixels of the photodiode array.
Additionally, in the horizontal type CMOS image sensor according to the related art, it is very difficult to achieve the optimized process of concurrently forming the photodiode and the transistor.